CN103066980A - Photoelectric switch - Google Patents
Photoelectric switch Download PDFInfo
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- CN103066980A CN103066980A CN2012104031118A CN201210403111A CN103066980A CN 103066980 A CN103066980 A CN 103066980A CN 2012104031118 A CN2012104031118 A CN 2012104031118A CN 201210403111 A CN201210403111 A CN 201210403111A CN 103066980 A CN103066980 A CN 103066980A
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- light
- light projector
- pattern
- optoelectronic switch
- pulse duration
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/941—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated using an optical detector
- H03K17/943—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated using an optical detector using a plurality of optical emitters or detectors, e.g. keyboard
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V8/00—Prospecting or detecting by optical means
- G01V8/10—Detecting, e.g. by using light barriers
- G01V8/20—Detecting, e.g. by using light barriers using multiple transmitters or receivers
Abstract
A transmitter (10) projects light in accordance with a specific light projecting pattern, selected by a pattern selecting portion (11), of three light projecting patterns A through C having mutually differing projected light periods and projected light pulse widths. A pulse width evaluating circuit (30) of a detector (20) detects, as a difference in pulse width of a detected light signal, the difference in the projected light pulse width of the light projecting pattern, based on the same light projecting pattern pulse width information as the transmitter (10), selected by a pattern selecting portion (21), to identify locally-emitted light versus interference light.
Description
Technical field
The present invention relates to a kind of optoelectronic switch that the detected object thing is detected according to the variation of light income.
Background technology
The optoelectronic switch of transmission-type comprises one group of light projector and light-receiving device, according to by the detected object thing by this light path cover have unmatchful light quantity to change to detect (for example, referring to patent documentation 1).Fig. 5 is the illustration figure when the transmission-type optoelectronic switch is used with 3 multi pack states.One side of the surveyed area that passes through at the detected object thing disposes light projector 100A～100C; Dispose light-receiving device 200A～200C at opposite side.In this example, light projector 100A and light-receiving device 200A are a pair of, light projector 100B and light-receiving device 200B are a pair of, light projector 100C and light-receiving device 200C are a pair of, for example, light-receiving device 200A only reacts the light signal generating that comes from light projector 100A, and does not wish that it is to coming from light projector 100B, the light signal generating reaction of 100C.But, between paired light projector and light-receiving device, do not carry out the information exchange beyond the light signal, therefore, which light projector light-receiving device can't distinguish the light signal accepted from.
Therefore, be with mutually respectively configuration of light projector and light-receiving device (configuration of zigzag ground) in the past, perhaps polarizing filter is installed on the light-receiving device, and will removes from the light of the light projector of adjacency.Existing background technology document
Patent documentation
Patent documentation 1: Japanese kokai publication hei 5-175817 communique
Summary of the invention
The problem that invention will solve
Because existing optoelectronic switch is aforesaid structure, so be configured in the zigzag situation, owing to dispose respectively light projector and light-receiving device in the both sides of surveyed area, thereby exist the distribution that comes from control device with elongated, perhaps produce because coming from the such problem of catoptrical interference of detected object thing.
In the situation that adopts polarizing filter, although by polarizing filter is installed, so that polarization angle becomes the right angle, thereby the light from the light projector on next door can be removed, but exist because light income is reduced to below half, detect apart from shortening such problem.
The present invention makes in order to solve aforesaid problem, and purpose provides a kind of in the situation that a plurality of multi packs use with optoelectronic switch, interferes even exist mutually, also can normally judge into light state or the optoelectronic switch of shading status.
Solve the means of problem
The optoelectronic switch of technical scheme 1 of the present invention comprises: light-projecting portion, light projector cycle and light projector pulse duration be separately in different a plurality of light projector patterns, and light projector pattern according to the rules carries out the light projector of this pulse duration periodically every this light projector to surveyed area; And light accepting part, it accepts from the light of described surveyed area and generates to be subjected to light pulse; With the pulse duration detection unit, whether its pulse duration that is subjected to light pulse that described light accepting part is generated is judged with the light projector pulse duration of the light projector pattern of described regulation is roughly the same, if roughly the same, just be judged as the only self-luminous of described light-projecting portion projection of being accepted by described light accepting part.
The optoelectronic switch of technical scheme 2 of the present invention has: band pass filter, detection section, low pass filter and identification part.Wherein, band pass filter, its light-projecting portion has the modulation portion that the light projector frequency of the pulse duration of light projector pattern is according to the rules modulated, and the light signal that its light accepting part is just accepted extracts the modulating frequency the used signal as centre frequency in described modulation portion; Detection section carries out rectification to the signal that described band pass filter extracts; Low pass filter for described detection section rectification signal, by described modulation, will be reduced to the frequency content of this signal stack till the frequency characteristic of regulation magnitude always; The signal that extract described low pass filter the identification part is identified and is exported with the threshold value of regulation and is subjected to light pulse.
The optoelectronic switch of technical scheme 3 of the present invention comprises detection unit, this detection unit, be judged to be in the self luminous situation by the pulse duration detection unit, stated number is added in the count value, and from the moment of this judgement, if the light projector cycle of regulation light projector pattern through during do not have next to judge, then from described count value, deduct setting, and according to described count value to having or not the detected object thing to judge in the surveyed area.
The optoelectronic switch of technical scheme 4 of the present invention comprises the pattern selection portion, and this pattern selection portion is accepted indication from the outside, and selects the light projector pattern of regulation in the middle of a plurality of light projector patterns.
The optoelectronic switch modulation portion of technical scheme 5 of the present invention is roughly modulated light projector during being roughly 1.0 μ s, low magnitude during with high-magnitude the modulation period of 1.5 μ s.
The invention effect
According to technical scheme 1 of the present invention, whether the light projector pulse duration of light projector pattern is roughly the same according to the rules by judging the pulse duration that is subjected to light pulse that light accepting part generates and light-projecting portion, determine whether self-luminous, so at a plurality of multi packs and in the situation about using, even exist mutual interference also can normally judge into light state or shading status with optoelectronic switch.
According to technical scheme 2 of the present invention, because pulse is modulated to light projector, and in the light accepting part side with modulating frequency as centre frequency and carry out bandpass filtering treatment, even so light projector pattern according to the rules, change in the situation of light projector pulse duration, also can make the amplitude of the signal that the band pass filter processed roughly the same, by making the low-pass filtering treatment till the frequency content that superposes on this signal is reduced to the regulation magnitude, the difference of the light projector pulse duration of light-projecting portion side can be detected in the light accepting part side as the difference that is subjected to light impulse length.
According to technical scheme 3 of the present invention, because be determined with without the detected object thing based on the count value of carrying out lifting according to the result of determination of pulse duration detection unit, so even existence is mutual interference light or self luminous decision error, also can in the lower situation of this frequency, prevent into light state or the erroneous judgement of shading status.Therefore, whether be such light projector cycle of the frequency step-down of self luminous decision error and set the light projector pattern for by selecting to make, can further reduce the erroneous judgement of light inlet/shading status.
According to technical scheme 4 of the present invention, accept from the indication of outside the light projector pattern to be selected such execution mode because made, so the user can freely use the optoelectronic switch multi pack, can improve versatility and autgmentability.
According to technical scheme 5 of the present invention because to during the high-magnitude carrying out high frequency modulation with 1.5 μ s roughly during 1.0 μ s roughly, the low magnitude, so on one side can reduce the impact of interference light, Yi Bian guarantee sufficient signal magnitude.
Description of drawings
Fig. 1 is the structural representation block diagram of the optoelectronic switch of embodiments of the present invention 1.
Fig. 2 is the chart of three kinds of light projector patterns of the optoelectronic switch of explanation embodiments of the present invention 1.
Fig. 3 is the example chart that is subjected to light signal of the light projector pattern of 1 optoelectronic switch according to the embodiment of the present invention.
Fig. 4 is the action example chart of the optoelectronic switch of embodiments of the present invention 1.
Fig. 5 is the figure of expression setting example when three transmission-type optoelectronic switches are used with the multi pack state.
Symbol description
1 optoelectronic switch
10 light-projecting portions
11,21 pattern selection portions
12 oscillating circuits
13 modulation circuits
14 drive circuits
20 light accepting parts
22 photo detectors
The 23IV change-over circuit
24 amplifying circuits
The 25BPF circuit
26 detecting circuits
The 27LPF circuit
28 identification circuits
29 decision circuits
30 pulse duration decision circuits
31 forward-backward counters
100A～100C light projector
200A～200C light-receiving device.
Embodiment
Execution mode 1
Optoelectronic switch 1 shown in Figure 1 is to comprise being clipped in the light-projecting portion 10 of being arranged to face-to-face state between the surveyed area and the transmission-type optoelectronic switch of light accepting part 20, light accepting part 20 judges according to from the variation that detects the light quantity of regional light inlet whether the detected object object is arranged in the surveyed area.
In present embodiment 1, the structure when using imagining three these optoelectronic switches 1 of maximum multi packs describes.Three optoelectronic switch 1(are at this, be referred to as respectively optoelectronic switch 1A～1C) by different three light-projecting portions 10 of cycle of light projector pulse and pulse duration with based on cycle and the pulse duration of suffered light, to being that three light accepting parts 20 that self-luminous or interference light are distinguished consist of.
At this, so-called self-luminous refers to the light that the light accepting part 20 of optoelectronic switch 1A is accepted from the light-projecting portion 10 of same optoelectronic switch 1A.So-called interference light refers to that the light accepting part 20 of optoelectronic switch 1A is from optoelectronic switch 1A optoelectronic switch 1B in addition, the light that 1C accepts.
Fig. 2 shows light projector pattern A～C.The light projector pulse by with light projector pattern A～C jointly, take modulation period as T=2.5 μ s(modulating frequency 400kHz) formed by the pulse train of high frequency modulation.This modulation period t during by high-magnitude (H) be 1.0 μ s, low magnitude (L) during consisted of by 1.5 μ s.
The light projector pattern A that (a) of Fig. 2 illustrates is, establishes light projector cycle T A=90 μ s, and the light projector pulse of pulse duration 8.5 μ s is become 4 series impulses by high frequency modulation.
The light projector pattern B that (b) of Fig. 2 illustrates is, establishes light projector cycle T B=288 μ s, and the light projector pulse of pulse duration 28.5 μ s is become 12 series impulses by high frequency modulation.
The light projector pattern C that (c) of Fig. 2 illustrates is, establishes light projector cycle T C=972 μ s, and the light projector pulse of pulse duration 48.5 μ s is become 20 series impulses by high frequency modulation.
At this, modulation period t H during and the state when preferably considering during the L mutually to interfere and decided by the signal magnitude of light signal.In present embodiment 1, with modulation period t be made as in the situation of 2.5 μ s, if owing to become longer than 1.0 μ s during the H, the impact that produces because of interference just will become large; If shorten, then the signal magnitude will reduce and signal to noise ratio (S/N ratio) will worsen, thereby with being decided to be 1.0 μ s(during the H to a certain degree scope can be arranged), with being decided to be 1.5 μ s(during the L to a certain degree scope can be arranged).
In light-projecting portion 10, pre-recorded in the pattern selection portion 11 have light projector cycle that above-mentioned light projector pattern A～C is stipulated and the information of light projector pulse duration.And, which the pattern selection portion 11 of input of accepting to select from the outside light projector pattern A～C with selected light projector pattern to modulation circuit 13 indications.
In present embodiment 1, suppose that optoelectronic switch 1A selects light projector pattern A, optoelectronic switch 1B selects light projector pattern B, and optoelectronic switch 1C selects light projector pattern C.
Modulation circuit 13 is modulated into the clock signal of the some cycles of oscillating circuit 12 starting of oscillations according to the indicated light projector pattern of pattern selection portion 11.Even modulating frequency is not limited to 400kHz so long as the abundant high frequency of the frequency of the stray light of ratio imagination and noise gets final product.Drive circuit 14 will be by the pulse current Gong Give light-projecting component 15 of the light projector pattern of modulation circuit 13 output.And, by the LED(light-emitting diode) etc. the light-projecting component 15 that consists of to the surveyed area light projector.
In light accepting part 20, pre-recorded in the pattern selection portion 21 have with corresponding relevant light projector cycle, the light projector pulse duration of above-mentioned light projector pattern A～C and be subjected to the information of the decision condition of light impulse length.The details of each information will be narrated in the back.And the decision condition that is subjected to light impulse length and the light projector cycle of accepting to select from the outside which the pattern selection portion 21 of input light projector pattern A～C will meet selected light projector pattern indicate to decision circuit 29.In order to distinguish self-luminous and interference light, owing to must use the light projector pattern identical with paired light-projecting portion 10 and light accepting part 20, so the light accepting part 20 of optoelectronic switch 1A can be selected light projector pattern A, the light accepting part 20 of optoelectronic switch 1B can be selected light projector pattern B, and the light accepting part 20 of optoelectronic switch 1C can be selected light projector pattern C.
Photo detector 22 is made of photodiode etc., accepts the light from the direction of surveyed area, and the current value that will meet the light income magnitude is exported.The output current of photo detector 22 carries out the current-voltage conversion by IV change-over circuit 23, is amplified by amplifying circuit 24.
In advance at the BPF(bandpass filtering) set the modulating frequency identical with the modulation circuit 13 of light-projecting portion 10 (be 400kHz at this) in the circuit 25, this modulating frequency is made as centre frequency by the territory, to carry out the filtering processing from the output signal of amplifying circuit 24.Thus, use such as the frequency about 100kHz and remove origin in the stray light of luminous frequency conversion type fluorescent lamp etc. and noise etc.And, carry out rectification with the output signal of 26 pairs of BPF circuit 25 of detecting circuit.
27 pairs of output signals from detecting circuit 26 of LPF circuit carry out filtering and process, so that because the high-frequency composition that the high frequency modulation of light-projecting portion 10 sides has superposeed is reduced to the magnitude of needs.The signal that thus, can remove the high-frequency composition, will be subjected to is demodulated to has the signal that meets self luminous light projector pulse duration.
Identification circuit 28 will be compared by the threshold value that is subjected to light signal magnitude and predefined regulation of LPF circuit 27 outputs, with only exporting for the pulse of the above composition of threshold value of extracting.Even, no matter because light projector pattern A～C how amplitude all about equally, so this threshold value can be identical value.Certainly, threshold value can not fixed yet, the change that yet can suit.
Below, for light-projecting portion 10 in the light projector pulse duration used distinguish, utilize LPF circuit 27 and identification circuit 28 demodulation the pulse duration that is subjected to light signal call and be subjected to light impulse length.
(c) of (a)～Fig. 3 of Fig. 3 illustrates the light signal that is subjected to of LPF circuit 27 outputs; (c ') of (a ') of Fig. 3～Fig. 3 illustrates the light pulse that is subjected to of identification circuit 28 outputs.(a) of Fig. 3, (a ') be the chart of having selected the optoelectronic switch 1A of light projector pattern A; (b) of Fig. 3, (b ') be the chart of having selected the optoelectronic switch 1B of light projector pattern B; (c) of Fig. 3, (c ') be the chart of having selected the optoelectronic switch 1C of light projector pattern C.In addition, suppose all not contain in arbitrary chart interference light.
Because the light projector pulse duration is different among light projector pattern A～C, when it is carried out demodulation, as (a ')～Fig. 3 of Fig. 3 (c '), be subjected to light impulse length with difference according to the light projector pattern.Thereby, in decision circuit 29 described later, be subjected to the light projector pulse duration of the light projector pattern whether light impulse length set with machine itself suitable by judgement, just can distinguish self-luminous.
Decision circuit 29 comprises pulse duration decision circuit 30 and forward-backward counter 31.In addition, be subjected to the decision condition of light impulse length and throw photoperiodic information from pattern selection portion 21.
30 pairs of pulse duration decision circuits by identification circuit 28 outputs be subjected to light signal whether met by pattern selection portion 21 indicated decision conditions by light impulse length to judge, if meet, just be judged to be self-luminous, " 1 " is exported.This decision condition can be considered as higher limit and the lower limit of self luminous pulse duration, if being subjected to light impulse length is more than the lower limit and for below the higher limit, just be judged to be self-luminous, beyond the scope of this upper lower limit value, then be judged to be interference light if be.In the example of (a ')～Fig. 3 of Fig. 3 (c '), all in the scope of upper lower limit value, will be judged as self-luminous according to any light impulse length that is subjected to.
In present embodiment 1, the change along with respect to the magnitude of the light income of threshold value also will be changed by light impulse length.If the light income magnitude slightly larger than threshold value just will be shortened by light impulse length, if than the abundant large light income magnitude of threshold value, be subjected to light impulse length then will become roomy.For this reason, be necessary between pattern, to make in advance the light projector pulse duration to have to a certain degree poor for light accepting part 20, even distinguish in order to be subjected to the light impulse length change also can whether meet among light projector pattern A～C which to it.Therefore, as shown in Figure 2, between pattern, give the poor of 20 μ s, by in light projector pattern A, giving the light projector pulse duration 8.5 μ s; In light projector pattern B, give 28.5 μ s; Giving 48.5 μ s in light projector pattern C just can be with each light projector pattern to distinguished by light impulse length.
Forward-backward counter 31 is then counted when 30 output " 1 " of pulse duration decision circuit and is over; Then reduce when exporting " 1 " in during stipulating.In present embodiment 1, forward-backward counter 31 is made of the digital integrating circuit that increases/subtract counting that carries out 10 magnitudes.
In counting, will be made as during slightly longer than the light projector cycle after the just input " 1 " (for example throwing photoperiodic 1.1 times) during the regulation, then be made as later on identical with the light projector cycle during.Just after the input " 1 " during obtain longlyer, be the error count that produces because of the clocking error between light-projecting portion 10 and the light accepting part 20 in order to get rid of.
And decision circuit 29 carries out following action according to the Counter Value of forward-backward counter 31.
1. Counter Value is 0 o'clock, is judged to be shading status (state that the detected object thing is arranged)
2. Counter Value is 10 o'clock, is judged to be into light state (state that does not have the detected object thing)
3. Counter Value is 1～9 o'clock, keeps the judgement of front
In the situation that three optoelectronic switch 1 multi packs are used, under interference state, sneak into interference light in sometimes because of self-luminous and make and changed by light impulse length.At that rate, utilize pulse duration decision circuit 30 to take a decision as to whether self-luminous and sometimes then can produce mistake, because decision circuit 29 utilizes the reversible counting mode to carry out the determination processing of light inlet/shading status, thereby can get rid of the impact of some decision errors that produced by pulse duration decision circuit 30.Even, in the situation of the reversible counting of 10 magnitudes, if average decision error below 5 times then will can not produce the erroneous judgement of light inlet/shading status in theory.
For example, Counter Value at forward-backward counter 31 is " 10 ", the decision error that produces because of pulse duration decision circuit 30 recur 2 times (namely 2 throw photoperiodic during the output of " 1 " when not having) in situation, thereafter, if there is not decision error, the erroneous judgement that just can not produce light inlet/shading status.At this moment, " 10(enters light state) " → (decision error) because being changed to of Counter Value → " 9(enters light state) " → (decision error) → " 8(enters light state) " → (normal judge) → " 9(enters light state) " → (normal judge) → " 10(enters light state) ", so decision circuit 29 will be kept the judgement into light state.Therefore, optoelectronic switch 1 does not carry out misoperation.
Like this, for example when Counter Value is " 10 ", even the light impulse length that is subjected to that can't correctly carry out pulse duration decision circuit 30 because of noise or interference light judge, if the discrete words of decision error also can be kept the judgement into light state.On the contrary, when Counter Value is " 0 ", even the light impulse length that is subjected to that can't correctly carry out pulse duration decision circuit 30 because of noise or interference light judge, if the discrete words of decision error also can be kept the judgement of shading status.
Namely, even because decision error occurs in interference, because if Counter Value does not become " 0 " or becomes " 10 " from " 0 " from " 10 ", just can be considered as regular event, below will being suppressed to a certain degree because of the Frequency of mutually interfering the decision error of the pulse duration decision circuit 30 that causes, the impact that also can not interfered.
Light projector cycle T A～TC is because the greater light projector consistent frequency decline on opportunity of the ratio in this cycle.Again, this when being integral multiple, the slow cycle must be consistent with the opportunity in fast period, so be necessary to be set to slightly depart from the value of integral multiple.Therefore, in present embodiment 1, poor (ratio) between light projector cycle T A～TC is set as than 3 times of large to a certain degree value slightly large values.
But, if strengthen light projector cycle ratio each other, A compares with the light projector pattern, the response speed of light projector pattern B is just with slack-off, and, because compare the response speed of light projector pattern C with light projector pattern B slack-off, so preferably, sets the light projector cycle according to taking into account the decision error Frequency and the response speed that cause because of interference.
In addition, because have the slack-off characteristic of response speed that the response speed of comparing light projector pattern B with light projector pattern A is slack-off, compare light projector pattern C with light projector pattern B, using in the situation of optoelectronic switch 1 separately, preferably select light projector pattern A.According to same reason, when under the state with two optoelectronic switch 1 multi packs, using, preferably select light projector pattern A, B.
And, in the above description, although imagine three of maximum multi packs, be not limited thereto, also can prepare four different light projector patterns, and use under the state with optoelectronic switch 1 multi pack more than four.
At this, use Fig. 4, to two optoelectronic switch 1A of multi pack of present embodiment 1, the action example when using under the 1B state describes.
(a) of Fig. 4 is the light signal of light-projecting component 15 emissions of optoelectronic switch 1A, and (b) of Fig. 4 is the light signal of light-projecting component 14 emissions of optoelectronic switch 1B.Light projector pulse is separately modulated by high-frequency, owing to illustrated words will be difficult to see clearly, so represent with the waveform before the high frequency modulation on chart.(c) of Fig. 4 is optoelectronic switch 1A, the light signal that each photo detector 22 of 1B is accepted, because light projector pattern A, the light projector of B is the state of mutually interfering, thereby becomes same waveform.(d) of Fig. 4 is the Counter Value of the forward-backward counter 31 of optoelectronic switch 1A, and (e) of Fig. 4 is the Counter Value of the forward-backward counter 31 of optoelectronic switch 1B.In addition, the transverse axis of (a)～Fig. 4 of these Fig. 4 (d) is time ［ ms ］, and the time of each chart is synchronous.
At first, the action of optoelectronic switch 1A described.
(c) of Fig. 4 is subjected to light pulse P1, owing to be to contain the interference state of the light projector pulse of light projector pattern A in the light projector pulse of light projector pattern B, so will become the above pulse duration of higher limit of the decision condition of light projector pattern A.Therefore, the pulse duration decision circuit 30 of optoelectronic switch 1A is subjected to light pulse P1 to be judged to be interference light (decision error) this, and " 1 " is not input to forward-backward counter 31.At this, if be T1 during the light projector cycle equal length of light projector pattern A, if forward-backward counter 31 than this period T1 slightly long during T2(T2=T1 * 1.1 for example) do not have " 1 " input, then (C1A of Fig. 4 (d)) reduces Counter Value just from " 10 " to " 9 ".Decision circuit 29 is owing to when Counter Value is " 9 ", be to keep last acts of determination to set, so be judged to be into light state.
Be subjected to light pulse P2, P4 also similarly processes with being subjected to light pulse P1.
These are subjected to light pulse P1, and P2, the next one of P4 are subjected to light pulse owing to close with the light projector pulse duration of light projector pattern A, thereby satisfy decision condition and be judged as self-luminous, and " 1 " is input to forward-backward counter 31.Thereby Counter Value becomes " 10 " and continues to be judged as into light state.
Secondly, the action of optoelectronic switch 1B described.
(c) of Fig. 4 is subjected to light pulse P1, P2 is the interference state that contains the light projector pulse of light projector pattern A in the light projector pulse of light projector pattern B, owing to be subjected to the light projector pulse duration of light impulse length and light projector pattern B close, thereby the pulse duration decision circuit 30 of optoelectronic switch 1B is subjected to light pulse P1 with these, P2 is judged to be self-luminous, and " 1 " is inputed to forward-backward counter 31.But, because Counter Value has become the upper limit " 10 ", so Counter Value will be less than changing.Because Counter Value is " 10 ", thereby decision circuit 29 is judged to be into light state.
Being subjected to light pulse P3 is light projector pattern A, the interference state of the light projector segment pulse of B stack, more specifically, be in light projector pattern B by the rising during the light projector of high frequency modulation near and descend near, A does not produce interference with the light projector pattern; And do not belong to this situation, among the light projector pattern B by the central portion during the light projector of high frequency modulation near, produce the state of interfering with light projector pattern A.In other words, light projector pattern B will carry out following transition: non-interference → interference → non-interference.At this moment, BPF circuit 25 plays a part to make the part that is subjected to not produce interference among the light pulse P3 to pass through; In the middle of the light projector pattern B, just the overlapping part with light projector pattern A is attenuated by BPF circuit 25.At this, in optoelectronic switch 1A, because the lower limit that is not less than decision condition separately by near near the rising during the light projector of high frequency modulation and two places (non-interference portion) descending among the light projector pattern B (simultaneously, be no more than higher limit), thereby " 1 " is transfused to secondary in forward-backward counter 31.To this, in optoelectronic switch 1B, owing to become below the lower limit of decision condition by light impulse length, so 30 of the pulse duration decision circuits of optoelectronic switch 1B are subjected to light pulse P3 to be judged to be interference light (decision error), and " 1 " do not inputed to forward-backward counter 31.At this, if will with the light projector cycle equal length of light projector pattern B during be made as T3, if than T3 during this period slightly long during T4(T4=T3 * 1.1 for example) not have input " 1 ", just (C3B of Fig. 4 (e)) reduces forward-backward counter 31 from " 10 " to " 9 " with Counter Value.At this moment, decision circuit 29 is kept the judgement into light state.Even, in optoelectronic switch 1B, owing to only be subjected to the judgement of light impulse length in the light projector pulse period of each light projector pattern B, so even near near two places (non-interference portion) that reached the rising during the light projector of high frequency modulation descending among the light projector pattern B are lower than the separately lower limit of decision condition, because mutual interval is shorter fully than light projector pulse period of light projector pattern B, the action as twice is reduced Counter Value will not occur.
Being subjected to light pulse P4 is light projector pattern A, the interference state that the light projector pulse of B links to each other, thereby will become more than the higher limit of decision condition of light projector pattern B by light impulse length.Therefore, 30 of the pulse duration decision circuits of optoelectronic switch 1B are subjected to light pulse P4 to be judged to be interference light (decision error), and " 1 " are not inputed to forward-backward counter 31.But as mentioned above, T4 reduced (that is, to the minimizing of C3B) during the next time wait of forward-backward counter 31 inputs " 1 " was slightly longer than the light projector cycle, and will exclude because of the error count that clocking error produces.In this, owing to can absorb the deviation that produces because of clocking error, the number of times after is more then got back to common action, wait for identical with the light projector cycle during T3 reduce (that is, the minimizing to C4B from C3B) and get final product.
Be subjected to the next one of light pulse P4 to be subjected to light pulse, the next one is subjected to light pulse again, because equate with the light projector pulse duration of light projector pattern B, so be judged as self-luminous, and " 1 " is inputed to forward-backward counter 31.Thereby Counter Value is counted as " 9 ", " 10 ", continues to be judged as into light state.
Like this, although in optoelectronic switch 1A for being subjected to light pulse P1, P2, P4, produce the decision error of self-luminous/interference light; For being subjected to light pulse P3, P4 to produce the decision error of self-luminous/interference light, if still Counter Value does not become " 0 ", then entering light state will be maintained in optoelectronic switch 1B.
Thereby, at two optoelectronic switch 1A, between the 1B, there are 2～3 times because mutually interfering the decision error that produces to become in 10 times the judgement, if the number of times of this degree, even the erroneous judgement of light inlet/shading status also can not occur in so wrong erroneous judgement.
More than, according to execution mode 1, optoelectronic switch 1 comprises: modulation circuit 13, light-projecting portion 10, BPF circuit 25, detecting circuit 26, LPF circuit 27, identification circuit 28 and pulse duration decision circuit 30.Modulation circuit 13 according to light projector cycle and light projector pulse duration separately among different three light projector pattern A～C, by the light projector pattern of pattern selection portion 11,21 selected regulations, the light projector of this pulse duration is carried out high frequency modulation; Light-projecting portion 10 with each this light projector cycle with high frequency modulation this pulse duration carry out light projector to surveyed area; The modulating frequency that 25 pairs of acceptance of BPF circuit are used from the light of surveyed area and by modulation circuit 13 is extracted as the signal of centre frequency; Detecting circuit 26 carries out rectification with the signal that BPF circuit 25 extracts; 26 rectifications of LPF circuit 27 transference detecting circuits the high-frequency composition of signal stack be reduced to the regulation magnitude; Identification circuit 28 also will be exported by light pulse the threshold value that is subjected to light signal to be distinguished into regulation that LPF circuit 27 extracts; Whether the light projector pulse duration of the pulse duration that is subjected to light pulse of 30 pairs of identification circuits of pulse duration decision circuit 28 output and the light projector pattern of regulation is roughly the same judges, if roughly the same, just judge into the self-luminous of only light-projecting portion 10 projections of accepting with light accepting part 20.For this reason, in three situations about using of optoelectronic switch 1 maximum multi packs, even owing to exist mutual interference also can distinguish self-luminous, so can normally be into light state or the judgement of shading status.
Even, in execution mode 1, utilize 13 pairs of light projector pulses of modulation circuit to carry out high frequency modulation with 400kHz, but be not limited to this, also can as existing optoelectronic switch, not carry out high frequency modulation.If light projector pattern A for example carries out the light projector of 8.5 μ s to each light projector cycles 90 μ s.
Do not carrying out in the situation of high frequency modulation, the major part of existing optoelectronic switch is that BPF circuit 25 has to make and throws photoperiodic frequency by such frequency characteristic.Therefore, if according to light projector pattern A～C light projector pulse width variation, the amplitude of the output signal of BPF circuit 25 will have larger variation according to light projector pattern A～C.
Therefore, preferably, make to have such as what allow BPF and pass through the frequency characteristic of zone comparatively broad, so that the amplitude of the output signal of BPF circuit 25 can not carry out larger variation according to light projector pattern A～C.But owing to the noise that is subjected to mix in the light signal also passes through easily, thereby the S/N ratio will worsen.
To this, carrying out like that in the situation of high frequency modulation as described above, because BPF circuit 25 has the frequency characteristic that the frequency of the high frequency modulation of making is passed through, even so according to the light projector pattern A～C light projector pulse duration is become 8.5,28.5,48.5 μ s, the output signal of BPF circuit 25 also will become amplitude about equally.Therefore, be arranged to make the high-frequency composition that superposes by high frequency modulation to be reduced to the frequency characteristic of regulation magnitude in LPF circuit 27, the difference of the pulse duration that is subjected to light signal processed as LPF because of the difference of the light projector pattern of light projector pulse duration can be detected.
In addition, in execution mode 1, decision circuit 29 has forward-backward counter 31, this forward-backward counter 31, be judged to be in the self luminous situation by pulse duration decision circuit 30, the counting of Counter Value is over, if light projector cycle of the light projector pattern of regulation from the moment of this judgement roughly through during do not have nextly to judge, then Counter Value is reduced, judge the structure that has or not the detected object thing in the surveyed area according to the Counter Value of forward-backward counter 31.For this reason, though by 30 pairs of pulse duration decision circuits be mutual interference light or self-luminous carry out be determined with mistake, in the low situation of the frequency of this decision error, still can prevent into light state or the erroneous judgement of shading status.Therefore, in execution mode 1, utilize this characteristic of forward-backward counter 31, whether become low the sort of light projector cycle T A～TC as light projector pattern A～C by selecting if being the frequency of self luminous decision error, can further reduce the erroneous judgement of light inlet/shading status.
In addition, in execution mode 1, owing to be that pattern selection portion 11,21 is set, so that each optoelectronic switch 1 can be selected the structure of light projector pattern A～C, so the user can freely with optoelectronic switch multi pack and use, can improve versatility and autgmentability.
But, the user need not to select the light projector pattern to come optoelectronic switch 1 is set, the user also can be by the input light projector pulse duration identical with the light projector cycle, and the light projector pattern is set to structure in the optoelectronic switch 1, and the light projector pattern of perhaps not establishing in advance regulation in the optoelectronic switch 1 is also passable.In predefined situation, pattern selection portion 11, the 21st, unwanted.
Even, in the configuration example of Fig. 1, from the IV change-over circuit 23 of light accepting part 20 to identification circuit 28, no matter light projector pattern A～C all is set as identical circuit structure, but being not limited thereto, also can be the structure of for example according to light projector pattern A～C the frequency characteristic of LPF circuit 27 being switched.Particularly, the information output of light projector pulse duration that will be corresponding with pattern selection portion 21 selected light projector pattern A～C is to LPF circuit 27, LPF circuit 27 one sides allow the frequency content of light projector pulse duration pass through, one side carries out the filtering that utilizes high frequency modulation to remove the high-frequency composition of stack is processed, to improve the performance of optoelectronic switch 1.
In addition, in the above description, although the situation that is applicable to the transmission-type optoelectronic switch take the structure with execution mode 1 is not limited thereto as example is illustrated, also go for the optoelectronic switch of the other types such as reflection-type.
In addition, concrete structure is not limited to the structure of above-mentioned execution mode 1, says nothing of design alteration of not breaking away from aim scope of the present invention etc. and all comprises in the present invention situation.
Claims (5)
1. an optoelectronic switch is characterized in that, comprising:
Light-projecting portion, in light projector cycle and light projector pulse duration respectively in different a plurality of light projector patterns, light projector pattern according to the rules carries out the light projector of this pulse duration to surveyed area in each this light projector cycle;
Light accepting part, it accepts from the light of described surveyed area and generates to be subjected to light pulse; With
The pulse duration detection unit, whether its pulse duration that is subjected to light pulse that described light accepting part has been generated is judged with the light projector pulse duration of the light projector pattern of described regulation is roughly the same, if roughly the same, just be judged as the only described light-projecting portion that has been subjected to by described light accepting part light projector self-luminous.
2. optoelectronic switch according to claim 1 is characterized in that,
Light-projecting portion has modulation portion, and described modulation portion is modulated the frequency of the light projector of the pulse duration of light projector pattern up to specification,
Light accepting part has:
Bandpass filtering section, it extracts the signal that the employed modulating frequency of described modulation portion is made as centre frequency in the signal of suffered light;
Detection section, it carries out rectification to the signal that described band pass filter extracts;
Low-pass filtering section, its make described detection section rectification signal have the frequency characteristic that makes the frequency content that is superimposed on this signal by described modulation be reduced to the regulation magnitude;
Identification part, its signal that described low pass filter has been extracted with the threshold value of regulation are identified and are exported and be subjected to light pulse.
3. optoelectronic switch according to claim 1 and 2 is characterized in that, comprises detection unit,
This detection unit, stated number is added on the count value being judged to be in the self luminous situation by the pulse duration detection unit, nextly do not judge if having during photoperiodic through the throwing of light projector pattern of regulation from the moment of this judgement, then from described count value, deduct setting, and judge having or not of detected object thing in the surveyed area according to described count value.
4. each described optoelectronic switch in 3 according to claim 1 is characterized in that comprise the pattern selection portion, this pattern selection portion is accepted indication from the outside, and selects the light projector pattern of regulation in the middle of a plurality of light projector patterns.
5. optoelectronic switch according to claim 2 is characterized in that, modulation portion is roughly during with high-magnitude modulates light projector the modulation period that is roughly 1.5 μ s during 1.0 μ s, the low magnitude.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011-232272 | 2011-10-21 | ||
| JP2011232272A JP5865669B2 (en) | 2011-10-21 | 2011-10-21 | Photoelectric switch |
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| Publication Number | Publication Date |
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| CN103066980A true CN103066980A (en) | 2013-04-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN2012104031118A Pending CN103066980A (en) | 2011-10-21 | 2012-10-19 | Photoelectric switch |
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| Country | Link |
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| EP (1) | EP2584703B1 (en) |
| JP (1) | JP5865669B2 (en) |
| CN (1) | CN103066980A (en) |
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| CN104749988A (en) * | 2013-12-26 | 2015-07-01 | 同方威视技术股份有限公司 | Photoelectric switch for object detection |
| CN105242326A (en) * | 2015-09-02 | 2016-01-13 | 浙江工商大学 | Variable-frequency tracking infrared correlation type pedestrian path passage target detection method |
| CN109298461A (en) * | 2018-09-05 | 2019-02-01 | 上海索迪龙自动化有限公司 | A kind of method that correlation type optoelectronic switch determines light projector state |
| CN110312342A (en) * | 2019-06-28 | 2019-10-08 | 上海索迪龙自动化有限公司 | The light projector of photoelectric sensor adjusts system |
| CN111095465A (en) * | 2017-11-27 | 2020-05-01 | 欧姆龙株式会社 | Multi-optical axis photoelectric sensor |
| CN114200534A (en) * | 2021-12-09 | 2022-03-18 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
| CN114200534B (en) * | 2021-12-09 | 2024-04-26 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
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| JP6289409B2 (en) * | 2015-03-24 | 2018-03-07 | アズビル株式会社 | Photoelectric sensor |
| JP6731251B2 (en) * | 2015-12-25 | 2020-07-29 | パナソニック デバイスＳｕｎｘ株式会社 | Photoelectric sensor |
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| CN104749988A (en) * | 2013-12-26 | 2015-07-01 | 同方威视技术股份有限公司 | Photoelectric switch for object detection |
| CN104749988B (en) * | 2013-12-26 | 2017-12-05 | 同方威视技术股份有限公司 | Optoelectronic switch for object detection |
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| CN109298461A (en) * | 2018-09-05 | 2019-02-01 | 上海索迪龙自动化有限公司 | A kind of method that correlation type optoelectronic switch determines light projector state |
| CN110312342A (en) * | 2019-06-28 | 2019-10-08 | 上海索迪龙自动化有限公司 | The light projector of photoelectric sensor adjusts system |
| CN114200534A (en) * | 2021-12-09 | 2022-03-18 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
| CN114200534B (en) * | 2021-12-09 | 2024-04-26 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2013090302A (en) | 2013-05-13 |
| JP5865669B2 (en) | 2016-02-17 |
| EP2584703B1 (en) | 2016-06-22 |
| EP2584703A1 (en) | 2013-04-24 |
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Application publication date: 20130424 |